Perhaps a better question to ask would be why you need to indicate both hyphenation points and ligation points in text that is going to be collated.
Because one would want to:
- prepare documents for correct rendering (including both ligatures and hyphenation capabilities easily rendered in simple text browsers without using any lexical analysis) and use such prepared document as the prefered form for archiving, and then want to
- have such prepared corpus still usable for full-text searches...
